On the Balance Belt, I think, the proper clearance is more important then the tension. And, of course, proper orientation of those thick cone-like washers. It's a little PITA to adjust the BB, but after 2-3 belt replacements, it becomes easier. OP, don't rush - be patient and persistent. Have a stimulating drink, not energizing one (like Red Bull). Watch some youtube videos posted by a German dude named Jurgen, who fixes the 944's with such an ease!
There is another "local" guy, who explains it very well:
https://www.youtube.com/watch?v=iBxOboQNQ6U&pp=ygUcOTQ0IGJhbGFuY2UgYmVsdCByZXBsYWNlbWVudA%3D%3 D